1. Field of the Invention
The present invention relates to an apparatus for determining a degree of fatigue of a human body.
2. Description of the Prior Art
In general a swelling can frequently be seen on the leg, and in particular, on the calf of a person when it becomes fatigued in case where the person works while standing for longer period of time, for instance. Such swelling is caused by the reason that a body water or a lymphatic fluid is congested, not smoothly returned to the main body part of the person, under the effect of the gravity. The same swelling can also be seen when the person works while sitting down or the person sits with his legs crossed for longer period of time. In the latter case, bending the legs of the person for longer period of time makes reduced flow of blood and lymphatic fluid at an articulation part of the body, and then, the body water or lymphatic fluid can not smoothly be returned to the main body part. In such manner the swelling can occurs with the fatigue when the person works while keeping the same posture for longer period of time. In any case the gravity is the essential factor that can makes the body water congested. Therefore it can generally be said that the swelling occurs more or less for every person during the time of a day that the person get out of the bed, and the swelling gradually accumulates.
Although the swelling can occur for every person, it is normally restored by the next day. This is due to the fact that the body water becomes spread to the whole body of the person while he is sleeping or lying in the bed.
Such swelling starts to occur at the time the person gets up in the morning and gradually accumulates to reach the maximum at a certain time instance. Such swelling, however, starts to restore after the person goes to bed and is completely restored to substantially same level as that when the person got up in the morning of the previous day. The degree of swelling is changed depending on the activity of the person in a day, and it is not uniform, but different for each of the persons. In addition the sensitivity to the swelling is varies for each of the persons.
Therefore it may happen that in spite of a swelling not restored and a fatigue left accumulated on the next day a person does not feel such swelling so that the he forcibly continues to work, with the result that his health is injured. Alternatively there may be such case where a person feels a swelling on his leg, but he takes an optimistic view of restoration of the swelling on the next day, with the result that he loses sight of a symptom of a critical disease.
In order to obviate such possibility it is preferred to have an apparatus for objectively determining a degree of fatigue of a person. Unfortunately none of such apparatus has been available in the prior art.
In view of the above it is an object of the present invention is to provide an apparatus for simply determining a degree of fatigue of each of persons.
In order to attain such object the present invention provides an apparatus for determining a degree of fatigue of a human body, comprising: two pairs of electrodes; an electric current source; a voltage measuring unit; an arithmetic unit; a storage unit; and a display unit,
whereby said two pairs of electrodes are configured to contact with a body of a person under test;
said electric current source feeds a measurement current via selected ones of said electrodes;
said voltage measuring unit measures a voltage between another selected ones of said electrodes;
said storage unit stores a bioelectrical impedance calculated by said arithmetic unit and a reference value;
said arithmetic unit calculates the bioelectrical impedance based on the measurement value from said voltage measuring unit and a degree of fatigue of the person under test by comparing the currently measured value of the bioelectrical impedance with the reference value of the bioelectrical impedance stored in the storage unit; and
said display unit indicates the degree of fatigue of the person under test.
According to one embodiment of the present invention, said display unit graphically indicates the transition of change in degree of fatigue.
According to another embodiment of the present invention, the graph displayed on said display unit represents the transition of change in degree of fatigue on the basis of the bioelectrical impedance as measured in the morning.
According to further embodiment of the present invention, the graph displayed on said display unit represents the transition of change in degree of fatigue on the basis of the bioelectrical impedance as measured in the evening or night.
According to yet further embodiment of the present invention, said reference value of bioelectrical impedance is set before a certain action is carried out by a person under test, and said display unit indicates the degree of fatigue before and after such action by comparing the currently measured value of the bioelectrical impedance with the reference value of the bioelectrical impedance stored in the storage unit.
According to another aspect of the present invention, there is provided an apparatus for determining a degree of fatigue based on the swelling of a human body, comprising: two pairs of electrodes; an electric current source; a voltage measuring unit; an arithmetic unit; a storage unit; and a display unit,
whereby said two pairs of electrodes are configured to contact with a body of a person under test;
said electric current source feeds a measurement current via selected ones of said electrodes;
said voltage measuring unit measures a voltage between another selected ones of said electrodes;
said storage unit stores a bioelectrical impedance calculated by said arithmetic unit and a reference value;
said arithmetic unit calculates the bioelectrical impedance based on the measurement value from said voltage measuring unit and a degree of swelling of the person under test by comparing the currently measured value of the bioelectrical impedance with the reference value of the bioelectrical impedance stored in the storage unit; and
said display unit indicates a degree of swelling of the person under test.
According to one embodiment of the present invention, said display unit graphically indicates the transition of change in degree of swelling.
According to another embodiment of the present invention, the graph displayed on said display unit represents the transition of change in degree of swelling on the basis of the bioelectrical impedance as measured in the morning.
According to further embodiment of the present invention, the graph displayed on said display unit represents the transition of change in degree of swelling on the basis of the bioelectrical impedance as measured in the evening or night.
According to yet further embodiment of the present invention, said reference value of bioelectrical impedance is set before a certain action is carried out by a person under test, and said display unit indicates the degree of swelling before and after such action by comparing the currently measured value of the bioelectrical impedance with the reference value of the bioelectrical impedance stored in the storage unit.
According to yet further embodiment of the present invention, said reference value of the bioelectrical impedance represents an average change in amount of interstitial fluid that is the difference between average values for a plurality of measurements in every morning and in every night.
According to yet further embodiment of the present invention, said average change in amount of interstitial fluid is updated every time when the bioelectrical impedance is measured.
According to yet further embodiment of the present invention, said electric current source selectively feeds the measurement current having a plurality of frequencies.
According to yet further embodiment of the present invention, said electric current source feeds the measurement current having a single frequency.
According to yet further embodiment of the present invention, said two pairs of electrodes are configured to contact with both soles of the person under test.
According to yet further embodiment of the present invention, said two pairs of electrodes are configured to contact with a calf of the person under test.